Research has shown that social interaction and the development of friendships is important in promoting academic, personal and emotional development. Social interaction is a core difficulty for children and young people with Autism Spectrum Disorder (ASD). An increasing number of pupils with ASD are being educated within mainstream school where it is hoped that they will benefit from social opportunities with their peers and that the professionals working with them will be confident to support them (Keen and Ward, 2004). There is however growing evidence that school staff do not feel confident in supporting these pupils (House of Commons Education and Skills Committee, 2006; Robertson, Chamberlain and Kasari, 2003) and that this population of children are vulnerable to experiencing significantly poorer academic and social and emotional outcomes than their peers (Department for Education, 2012a; Humphrey and Lewis, 2008; Howlin and Goode, 1998). Teaching assistants (TAs) are often employed by schools to support pupils with ASD however research has suggested that the deployment of TAs might actually compound social interaction difficulties (Humphrey and Symes, 2011; Blatchford et al., 2009). TAs are in a unique position to support the social interaction of the pupils they work with however there is limited research into how TAs can be best utilised to facilitate social interaction between pupils with ASD and their typically developing peers within the classroom. This study piloted a researcher developed intervention, Better Together and conducted a process and outcome evaluation in order to investigate potential outcomes for TAs and pupils and examine systemic factors which might support or impede the intervention’s implementation and sustainability. The Better Together intervention aimed to train TAs to facilitate social interaction between pupils with ASD and their mainstream peers. The study involved three TA: pupil pairings within a single mainstream primary school and a single project coordinator. An evaluation of the ‘Better Together’ intervention package was undertaking using a fully mixed, sequential, dominant status design. Information pertaining to TA confidence levels was gathered pre and post intervention through semi-structured questionnaires. Structured observations were undertaken pre and post intervention and after a school term to gather information about the rate, range, maintenance and success of facilitative strategies used by the TAs. Semi-structured interviews with the TAs and project coordinator were carried out in order to obtain information about the implementation and outcomes of the intervention. The Social Inclusion Survey was administered at three time points to ascertain whether any changes in the social inclusion of target pupils had occurred.13Data were analysed using descriptive statistics and thematic analysis. The findings from this small scale study suggest that the TAs had an increased rate and range of facilitative behaviours following the intervention and that there was a simultaneous increase in student interactions between pupils with ASD and their peers. These gains were sustained over time. The intervention was valued by staff and plans were made to extend the principles to other schools within the area through the establishment of a TA network of support. Core facilitators and barriers to the implementation of the intervention were explored and discussed and implications for future research and the role of the Educational Psychologist (EP) are considered.